The invention concerns a venting device for a housing, in particular a battery housing, in particular of a motor vehicle, with a gas-permeable membrane that is impermeable for liquids and that is attached to the housing and closes off tightly a venting opening of the housing.
Moreover, the invention concerns a method for producing a venting device of a housing, in particular a battery housing, in particular of a motor vehicle, in which a gas-permeable membrane that is impermeable for liquids is attached flat with a membrane edge to the housing so that it closes off tightly a venting opening of the housing.
Venting systems of batteries for electric vehicles are known in the market. These venting systems have the function to compensate pressure fluctuations, caused in the battery housing during operation, in that gas from the battery housing can pass to the exterior through the venting system or air can flow into the battery housing from the exterior. This pressure compensation prevents that the battery housing is permanently plastically deformed and possibly becomes leaky. The venting system has a venting opening for the battery housing. The venting opening is covered by a flat rigid membrane that is permeable for gasses, in particular air, and gasses that are produced during operation of the battery. The membrane is impermeable for liquids, in particular water and battery acid. In this way, it is prevented that liquid out of the environment can flow into the battery housing and vice versa. Often it is necessary, for constructive or functional reasons, to arrange the venting system at the bottom side of the motor vehicle so that it is exposed to water and dirt, in particular mud, of the environment. In particular when used in off-road conditions, the venting system can become soiled to such an extent that its function is impaired. During standstill, the mud can form a crust on the membrane which causes a permanent impairment of the function of the venting system.